Slide valve

ABSTRACT

A slide valve in which the slide is supported in the valve chamber on links interengaged between the ends of the slide and the body, the body and slide having fluid passages, and the body passages having tubular seals having face-to-face sealing engagement with the slide. The slide is actuated by a lever extending through a wall of the body and engaged with the slide between its ends.

United States Patent Abdo [ Oct. 31, 1972 SLIDE VALVE [72] Inventor:Joseph T. Abdo, 25 Crest Rd. W.,

Rolling Hills, Calif. 90274 3,587,156 6/1971 Sorenson ..l37/625.48 X3,599,428 8/1971 Chaney et al ..l37/81.5 X 3,613,708 10/1971 Kampe et a1..l37/8l.5 3,621,880 11/1971 Jessee ..137/625.64 3,633,619 1/1972Eckerlin ..137/8l.5 X

Primary Examiner-Samuel Scott Attorney-Newton H. Lee, Jr.

[ 7] ABSTRACT A slide valve in which the slide is supported in the valvechamber on links interengaged between the ends of the slide and thebody, the body and slide having fluid passages, and the body passageshaving tubular seals having face-to-face sealing; engagement with theAllen et a1. 1 Slide The Slide is actuated a lever extending 3,136,3376/1964 Fox ..137/625.48 through a ll of the b d and engaged with theslide 3,191,627 6/1965 Courtney ..137/625.43 between i ends 3,348,57610/1967 Ackerman ..137/625.43 3,468,340 9/ 1969 DiCamillo ..l37/625.4821 Claims, 10 Drawing Figures /0 34 4 28 L 2/ 28 32 7 32 33 27 I9 22 2/\ji- 22 35 Z6 Z0 26 24 36 27 2a f L /7 4 \38 j? I J PATENTEMBIBI m23.701.365

SHEET 1 BF 5 JNVENT OR 5 BY JOJEPH Z A3120 2 zQ41 m5;

SHEET 2 0F 5 PAT-ENTEU our 3 1 I972 x x w k SLIDE VALVE BACKGROUND OFTHE INVENTION Typical valves useful in fluid pressure systems to controlflow have included a slide reciprocable in a valve chamber betweendifferent positions to control flow through passages in the body and inthe slide, leakage of fluid being prevented by tubular sealscircumscribing the body passages and having sealing end faces slidablyengaged with the slide.

The forces derived from fluid pressure have notoriously rendered theslide difficult to shift when the valve is employed in high pressureservice, unless actuator means were employed which were capable ofovercoming the friction of the slide in the body and the seals on theslide. Such actuators were usually either powerful pressure actuators orsolenoids or long levers.

While bearings interposed between the slide and the body are capable ofreducing the actuating force required to shift the slide, by reducingfriction between the slide and the body and distributing the forces, theuse of hearings, in the form of balls or rollers, also poses problems ofmanufacture, and in some cases, the bearings themselves produce frictionwhich must be overcome.

SUMMARY OF THE INVENTION The present invention is directed to slide typevalves, wherein tubular seals with sealing faces engage the slide, andwherein the slide is supported in the valve chamber in a novel mannerwhereby the slide is easy to shift. The present invention also providesa valve assembly, as aforesaid, which is easy to manufacture. Thus,simple actuator means may be employed and the valve, as a whole, iscomparatively inexpensive, yet efficient and easy to operate, eithermanually or automatically.

In accomplishing the foregoing, the valve of the present invention haslink means which support the slide in the valve chamber and which arerelatively friction free, so that the slide is easy to shift and themain frictional resistance to movement of the slide is the frictioncaused by pressure acting on the tubular seals to maintain their endfaces in sealing engagement with the companion face on the slide. Sincethe friction of such seals is a function of the pressure of the fluidmedium, the seals may be constructed so as to minimize this frictionunder various pressure conditions.

More particularly, the slide, in accordance with the invention issupported in the valve chamber adjacent to the ends of the slide bylinks which pivot or flex on axes transverse to the direction of v slidemovement and normal to the direction that force is applied to the slideby the tubular seals. These links may comprise tension elements orcompression elements supporting the slide or a combination of tensionand compression elements.

' These pivot or flexible links essentially suspend the slide in spacedrelation to the body walls forming the valve chamber and the links areso constructed and araanged as to offer little resistance to movement,notwithstanding that fairly large forces may be acting to force theslide towards a body wall, say the force derived from a number ofthousands of pounds of fluid pressure acting across an area on the slidedetermined by the cross-sectional area of the passage through thetubular seal in the inlet port when the valve is in the closedcondition. With the increased use of relatively high pressure fluidsystems, say between 1000 and 6000 PSI, more or less, reduction in thefriction caused by deflecting forces applied to the slide becomes evermore important.

The present invention also provides a novel and simple actuator meansfor shifting the slide longitudinally in the valve chamber, withoutrequiring that any portions of the slide extend from the body, so thatthe slide is free to move laterally to the extent and in the directionrequired by the links which support the slide in the chamber.

This invention possesses many other advantages, and has other purposeswhich may be made more clearly apparent from a consideration of forms inwhich it may be embodied. These forms are shown in the drawingsaccompanying and forming part of the present specification. They willnow be described in detail, for the purpose of illustrating the generalprinciples of the invention; but it is to be understood that suchdetailed descriptions are not to be taken in a limiting sense, since thescope of the invention is best defined by the appended claims.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a top plane of a valve made inaccordance with the invention;

FIG. 2 is an enlarged vertical section, as taken on the line 2-2 of FIG.1, showing the slide in a closed center condition in full lines, andshowing the slide paru'ally in broken lines in a position shifted to theright;

FIG. 3 is an enlarged vertical section, as taken on the line 3-3 of FIG.1;

FIG. 4 is a horizontal section, as taken on the line 4- 4 of FIG. 3;

FIG. 5 is a side elevation of another valve made in accordance with theinvention;

FIG. 6 is an enlarged horizontal section, as taken on the line 6-6 ofFIG. 5, showing the slide in a center position in full lines, andshowing the slide partially in broken lines in a position shifted to theright;

FIG. 7 is a vertical section as taken on the line 7-7 of FIG. 6;

FIG. 8 is a view corresponding to FIG. 2, showing still another valvemade in accordance with the invention;

FIG. 9 is a vertical section, as taken on the line 9-9 of FIG. 8;

FIG. 10 is a view corresponding to FIG. 2 and show ing still anothervalve made in accordance with the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to FIGS. 1 through 4,the valve of the invention will be seen to comprise a body 1 ofgenerally rectangular form and providing an internal valve chamber 2 inwhich is disposed a reciprocable slide 3 adapted to be actuated betweenvarious selected positions by actuator means including a lever 4. Inthis form of the valveassembly, the body 1 has a bottom wall 5, sidewalls 6, andend walls 7 formed as acasting, for example, to which a topwall 8 is applied by suitable fasteners 9, withsuitable sealing means 10being interposed between the top 8 and the side and end walls 6 and 7.

The present invention is directed to valves of the type in which theflow of fluid through the valve is controlled by tubular seals whichhave sealing end faces slidably engageable with opposed sealing faces onthe slide. Thus, in the embodiment now being described, one typical flowpattern is shown by way of illustration, but it will be understood thatother flow patterns are possible, and indeed, substantially the entirerange of flow patterns may be availed of which are typically found ineither reciprocating slide valves of the type here involved, or the morecomplex and less efficient spool valves.

More particularly, the illustrative flow pattern is the usual closedcenter, three position pattern involving an inlet port 1 l and returnport 12 on one side of the valve body, namely, the top side 8 in thepresent embodiment, and a pair of ports 13 and 14 are at the oppositeside or bottom of the body. The slide 3 has a pair of parallel ports orpassages 15 and 16 extending therethrough and spaced apart a distancecorresponding to the spacing of the ports 11, 12 and 13, 14, so thatthese ports are aligned upon longitudinal movement of the slide 3 to theleft, as seen in FIG. 2, and in addition, the slide has crossed ports 17and 18 spaced from one another and from the ports 15 and 16 forcommunication with the ports 11, 12 and l3, 14, upon movement of theslide to the right, as seen in FIG. 2.

Each of the ports 11, 12 and l3, l4 communicates with the passage 19which extends through a tubular seal element 20. These seal elementseach comprise a tubular body 21 disposed in a bore 22 and an enlargedannular head 23 disposed in an enlarged bore 24 having an end face 25slidably and sealingly engageable with the opposing flat face of therectangular slide 3. Annular sealing means are interposed in the bore 24between the tubular body 21 and the wall of bore 24, in the illustratedform of an O-ring seal 26 which is disposed between a pair of back uprings 27. In the bore 22 is a coiled compression spring 28 seating atthe bottom of the bore and on the inner end of the tubular seal toprovide a bias to maintain initial sealing engagement of the end facewith the slide 3. These tubular seals 20 have clearance in the bores 22and 24 so as to be capable of cooking in the bores, and in addition,these bores are of sufficient depth, relative to the length of the sealbody 21 and heads 23, as to allow the seals to move axially to thenecessary extent, all without disturbing the sealing engagement betweenthe end faces 25 and the engaged faces of the slide 3, as the slideshifts longitudinally, and as will be later described, also moveslaterally in the plane of the tubular seals 20.

Essentially, it will now be recognized, that the slide 3 is interposedbetween the opposing seal elements 20 in such a manner that forcesacting axially on the seals 20 have a tendency to cause friction betweenthe seals 20 and'the slide 3, and in addition, unbalanced forces appliedto the slide have a tendency to cause the slide 3 to cock in chamber 2.It is these forces in conventional valves which cause problems in theactuation of the slide between its selective positions. If the slide isdirectly guided on surfaces of the body, the drag friction is so highunder most useful pressures that the actuating forces become so high asto require complex and/or powerful actuator means. Under someconditions, even the use of bearings interposed between the slide andthe walls of the body may not be wholly satisfactory even though animprovement.

Thus, the present invention involves the concept of essentiallysuspending or supporting the slide within the cavity in such a mannerthat friction is minimized, and this is accomplished by the use of pivotlinks now to be described.

In the embodiment shown in FIGS. 1 through 4, such links are generallydenoted at L. These links L may be characterized as flexible pivot linksand are of generally U-shaped configurations, including spaced arms 30and a bight portion 31. The top wall 8 provides a pair of verticalshoulders 32 having arched edges 33, and the bight portions 31 of thelinks L are secured to the shoulders 32, by suitable fastenings 34 andclamping bars 35 which engage and clamp the bight portions 31 to theshoulders 32. The bars 35 have a bevel 36 opposing the arched edges 33to reduce the tendency of the links L to fail along a line of flexure.The ends of the arms 30 of the flexible links L are secured to oppositeend portions 37 of the slide 3 by a clamp bar 38 and fasteners 39. Theend portions 37 of the slide have arched edges 40 and the bar 38 isbevelled at 41 to minimize flex failure.

Various other flexible link configurations and fastenings may be availedof, it being understood that the object is to support the slide 3against engagement with internal body surfaces, whereby the onlyresistance to movement of the slide due to its support is the resistancecaused by flexing of the pivots, when the slide moves to the right toone open position, as shown in broken lines in FIG. 2, from the closedcenter position, or to the left to the other open position.

The seal elements 20 are capable of axial excursions sufiicient tocompensate for vertical movement of the slide caused by the linksupports L when the slide is shifted longitudinally by the actuatormeans now to be described.

The actuator means comprising the lever 4, are so constructed that theslide is not unbalanced in the body by an actuator rod extendingcoaxially from the slide and so that the slide can move in the compoundmanner illustrated in FIG. 2 and just described above.

Thus, the lever 4 extends through an opening in a side wall 6 of thebody 1, substantially normal to the slide 3 in its center position. Atits inner end, the lever supports suitable rollers 51 on a supportingpin 52, or other low friction means, engageable with the slide 3 toshift the latter. The slide 3, in the illustrated form, has a pair oflaterally projecting ears 53 providing a slot opening towards the lever4 and extended parallel to the axis of rotation of the rollers 51. Thelever 4 is pivotally supported on the body 1 by means of a pivot pin 54carried by a plate 55 which is secured to the body 1 by suitablefasteners 56.

Means are provided to form a seal between the body 1 and the lever 4,comprising a suitable bellows or diaphragm 57, the outer periphery 58 ofwhich is clamped against the body side wall 6 by the plate 55 and theinner periphery 59 of which is clamped against a shoulder 60 on thelever 4 by a clamp ring 61 and a nut 62 threaded on the lever 4. Now itis apparent that the lever 4 is shiftable between a center position andeither selected alternate position to 'znove the slide 3 longitudinallyin the valve chamber 2, and that the slide can also move relative to thelever as required by the links L.

A modified construction is shown in FIGS. 5 through 7. In thisembodiment, the link means L support the slide 103 on a side wall of thebody 1 and are in the form of pivotal links.

More particularly, the body 1 has the valve chamber 102 fonned therein,as in the previously described embodiment, as by casting the body unit,including the bottom 105, side walls 106 and end walls 107. However, theports 111, 112and 113, 114 are in the sides 106, and the actuator lever104 is supported on the top 108 of the body secured to the body byfasteners 109. In each of the ports 111, 112 and 113, 114 is a tubularseal element 120, the details of which require no further illustration.Since these ports are horizontally disposed and the slide moves in acompound motion horizontally, the actuator lever receiving ears or lugs153 are on the top of the slide for receiving the lever rollers 151. t

In this embodiment, the links are pivotal links, in the nature of hingeplates, including a body 130 having looped ears 131 adapted to straddlecomplemental portions 133 and 137 of the body and the slide and to bepivotally connected thereto by pivot pins 134 and 139 extending throughthe looped ears 131 of the links and through the portions 133 and 137 ofthe body.

The operation of the valve of FIGS. 5 through 7 is essentially the sameas the first described embodiment,

' and the only drag friction which need be overcome by virtue of thesupporting of the slide 103 will be the friction of the pivotalconnection, as the slide is shifted to the right, to the broken lineposition in FIG. 6, or to the left from the closed center position. Thevarious passages, not shown, for causing changes in flow between thevarious ports will be understood without further illustration ordescription.

Still another modification is shown in FIGS. 8 and 9 wherein the linksare pivot links having a knife edge pivot.

More particularly, the valve assembly is generally similar to that ofFIGS. 1 through 4, wherein the ports 211 and 212 are in the cover 208,and the ports 213 and 214 are in the bottom 205 of the body. In eachport 211, 212 and 213, 214 is one of the tubular seals 220, and hereagain, the specific porting of the slide 203 requires no specificillustration or description.

One significant point in this modified construction is that the links Lare a combination of tension link means and compression link means. Moreparticularly, the tension link means comprises a pair of spaced linkarms 230 connected at their ends by cross pieces 232. On the body top208 is a transversely extended lug 233 and an opposed lug 237 projectsfrom the end of the slide 203, these lugs 233 and 237 project betweenthe link arms 230 and are pivotally engaged by the respective crosspieces 232. The lug 233 has an upwardly divergent notch extendinglengthwise of the lug, and the lug 237 has a similar downwardlydivergent notch 239, and the opposing edges of the cross pieces 232 haveV-shaped or knife edges 232a engaged in the respective notches 234 and239, wherebyto pivotally support this end of the slide 203 with minimumfriction.

At the other end of the slide 203, the compression link means Lcomprises a plate 230a pivotally engaged at its upper end with the top208 and at its lower end with the slide 203. The top 208 has adownwardly divergent notch 234a extending transversely therein, and theslide 203 has a lug 237a formed with an upwardly divergent notch 239a.On the upper and lower ends of the link plate 230a are oppositely facingV- shaped or knife edges 232b engaged in the respective notches 234a and239a. A coiled tension spring 235 provides means normally biasing thisend of the slide 203 towards the top 108 to retain the compression pivotlink plate 230a in the notches just described. One end of the spring 235is connected to the slide 203 by a fastener 235a and the other end ofthe spring is connected to the body by a fastener 235b.

It will be recognized that in accordance with the embodiment of FIGS. 8and 9, knife edges are described, but, equivalently arched seats andlink ends may be employed, and the only friction necessary to beovercome during actuation of the slide is the negligable friction of theknife edge pivots.

In FIG. 10, still another embodiment of the invention, will be seen toinvolve the use of a pair of compression links L acting to resistmovement of the slide into engagement with the body in oppositedirections at opposite ends of the slide.

More particularly, the valve assembly of FIG. 10 is also generallysimilar to that of FIGS. 1 through 4, and includes ports 311 and 312 inthe top 308 of the valve body and ports 313 and 314 in the bottom wall305. As in the previously described embodiments, each of the ports 311,312 and 313, 314 has therein a tubular seal 220, and the specificporting by which fluid communicates through the slide 303 with therespective seals 320 requires no specific illustration.

In this embodiment, the link means L comprises a pair of compressionpivot links in the form of plates 330a, like the link 230a in FIGS. 8and 9, at the opposite ends of each of which is a knife edge 332aengaged in opposed divergent slots 334a in the respective body walls 305and 308 and opposed divergent slots 2340 in transversely extendedflanges 337 on opposite ends of the slide 307. Tension springs 335 areinterconnected between the slide end flanges 337 and the body walls 305and 308 by respective fasteners 335a and It is now apparent that thelinks 3300 support the slide 330 in such a manner that it is not biasedinto engagement with either the top or the bottom of the valve body, andthus, other than the friction between the end faces of the seals 320 andthe slide 303, the only frictional resistance to shifting of the slideis the negligable friction at the knife edges of the links.

In this embodiment, it will be understood that the slide will cockslightly on its axis end-to-end since the opposed links cause oppositevector motions, but the seals 320 will nevertheless maintain sealingengagement with the slide 303 when they are caused to cock in theirrespective bores, as is well known.

From the foregoing, it is apparent that the present invention providesan efficient valve from components which need not be made to closetolerances, it merely being necessary that the slide faces of thesealing members be flat to prevent leakage past the seal faces. Theseals will compensate for wear, as well as misalignment or lack ofparallelism. Most importantly, the valve will be easy to operate, due tocomparatively low friction at the slide supports or link means L. Inaddition, the construction of the actuator means and its connection tothe slide is such that no forces derived from the pressure fluid areapplied to the actuator means to create a load which must be overcome.

I claim:

1. A control valve comprising a body having top, bottom and side wallsand ends forming a closed chamber, a slide disposed in said chamber,inlet and outlet ports providing inlet and outlet passage means in saidwalls, said slide having ports providing passage means for conductingfluid between said ports, sealing means interposed between said body andsaid slide including tubular seal elements circumscribing certain ofsaid ports and having end. faces sealingly engaged with opposing facesthrough which other ports open for controlling the flow of fluid throughsaid passage means upon shifting of said slide in said chamber, saidseal elements each having its other end exposed to pressure of fluid inits port to force the end face of said sealing element into engagementwith said opposing face, pivot link means interengaged with said slideand said body supporting said slide in said chamber in spaced relationto said walls of said body for movement of said slide, and actuatormeans for shifting said slide.

2. A control valve as defined in claim 1, wherein said inlet port is inone wall of said body and said actuator means includes a lever extendingthrough an adjacent wall at a right angle to the axis of said inletport.

3. A control valve as defined in claim 1, wherein said inlet port is inone wall of said body and said actuator means includes a lever extendingthrough an adjacent wall at a right angle to the axis of said inletport, and including a pair of ears carried by said slide and rollermeans on said lever engaged between said ears.

4. A control valve as defined in claim 1, wherein said inlet port is inone wall of said body and said actuator means includes a lever extendingthrough an adjacent wall at a right angle to the axis of said inletport, said latter wall having an opening in which said lever isdisposed, and including a bellows seal clamped to said latter wall andto said lever.

5. A control valve as defined in claim 1, wherein said link meanscomprises a pair of tension links respectively connecting the ends ofsaid slide to a wall said body having said inlet port.

6. A control valve as defined in claim 1, wherein said link meanscomprises a tension link and a compression link respectively at oppositeends of said slide and engaged with opposing walls of said body.

7. A control valve as defined in claim 1, wherein said link meanscomprises a pair of compression links respectively at opposite ends ofsaid slide and engaged with a wall of said body.

8. A control valve as defined in claim 1, wherein said link meanscomprises flexible link members connected to the ends of said slide andto said body.

9. A control valve as defined in claim 1, wherein said link meanscomprises a flexible link member connected to one end of said slide andto said body and another link member connected to the other end of saidslide and to said body.

10. A control valve as defined in claim 1, wherein said link meanscomprises a pair of link plates respectively pivotally connected to theends of said slide and to said body.

11. A control valve as defined in claim 1, wherein said link meanscomprises a link plate pivotally connected to one end of said slide andto said body and another link member connected to the other end of saidslide and to said body.

12. A control valve as defined in claim 1, wherein said link meanscomprises a pair of link members respectively having knife edge pivotalengagement with the ends of said slide and with said body.

13. A control valve as defined in claim 1, wherein said link meanscomprises a link member having knife edge pivotal engagement with oneend of said slide and another link member connected to the other end ofsaid slide and to said body.

14. A control valve as defined in claim 1, wherein said link meanscomprises a tension link member having knife edge pivotal connectionwith one end of said slide and said body and another link memberconnected to the other end of said slide and to said body.

15. A control valve as defined in claim 1, wherein saidlink meanscomprises a compression link member having knife edge pivotal connectionwith one end of said slide and with said body and another link memberconnected to the other end of said slide and to said body.

16. A control valve as defined in claim 1, wherein said top wall has oneof said inlet and outlet ports therein, said bottom wall having theother of said inlet and outlet ports therein, and including means forremovably securing said top wall on said body, said link means beinginterengaged with said slide and said top wall.

17. A control valve as defined in claim 1, wherein said top wall has oneof said inlet and outlet ports therein, said bottom wall having theother of said inlet and outlet ports therein, and including means forremovably securing said top wall on said body, said link means beinginterengaged with said slide and said top wall, and said actuator meansincluding a lever extending into said chamber through a side wall ofsaid body.

18. A control valve as defined in claim 1, wherein one of said sidewalls has one of said inlet and outlet ports therein, the opposing sidewall having the other of said inlet and outlet ports therein, said linkmeans being interengaged with one of said side walls and said slide.

19. A control valve as defined in claim 1, wherein one of said sidewalls has one of said inlet and outlet ports therein, the opposing sidewall having the other of said inlet and outlet ports therein, said linkmeans being interengaged with one of said side walls and said slide, andsaid actuator means including a lever extending into said chamberthrough one of said top and bottom walls.

20. A control valve as defined in claim 1, wherein one of said walls hasone of said inlet and outlet ports therein and an opposing wall has theother of said inlet and outlet parts therein, said link means beinginterengaged between said slide and said one of said walls.

21. A control valve as defined in claim 1, wherein one of said walls hasone of said inlet and outlet ports therein and an opposing wall has theother of said inlet and outlet ports therein, said link means beinginterengaged between said slide and said one of said wall and saidopposing wall.

1. A control valve comprising a body having top, bottom and side wallsand ends forming a closed chamber, a slide disposed in said chamber,inlet and outlet ports providing inlet and outlet passage means in saidwalls, said slide having ports providing passage means for conductingfluid between said ports, sealing means interposed between said body andsaid slide including tubular seal elements circumscribing certain ofsaid ports and having end faces sealingly engaged with opposing facesthrough which other ports open for controlling the flow of fluid throughsaid passage means upon shifting of said slide in said chamber, saidseal elements each having its other end exposed to pressure of fluid inits port to force the end face of said sealing element into engagementwith said opposing face, pivot link means interengaged with said slideand said body supporting said slide in said chamber in spaced relationto said walls of said body for movement of said slide, and actuatormeans for shifting said slide.
 2. A control valve as defined in claim 1,wherein said inlet port is in one wall of said body and said actuatormeans includes a lever extending through an adjacent wall at a rightangle to the axis of said inlet port.
 3. A control valve as defined inclaim 1, wherein said inlet port is in one wall of said body and saidactuator means includes a lever extending through an adjacent wall at aright angle to the axis of said inlet port, and including a pair of earscarried by said slide and roller means on said lever engaged betweensaid ears.
 4. A control valve as defined in claim 1, wherein said inletport is in one wall of said body and said actuator means includes alever extending through an adjacent wall at a right angle to the axis ofsaid inlet port, said latter wall having an opening in which said leveris disposed, and including a bellows seal clamped to said latter walland to said lever.
 5. A control valve as defined in claim 1, whereinsaid link means comprises a pair of tension links respectivelyconnecting the ends of said slide to a wall said body having said inletport.
 6. A control valve as defined in claim 1, wherein said link meanscomprises a tension link and a compression link respectively at oppositeends of said slide and engaged with opposing walls of said body.
 7. Acontrol valve as defined in claim 1, wherein said link means comprises apair of compression links respectively at opposite ends of said slideand engaged with a wall of said body.
 8. A control valve as defined inclaim 1, wherein said link means comprises flexible link membersconnected to the ends of said slide anD to said body.
 9. A control valveas defined in claim 1, wherein said link means comprises a flexible linkmember connected to one end of said slide and to said body and anotherlink member connected to the other end of said slide and to said body.10. A control valve as defined in claim 1, wherein said link meanscomprises a pair of link plates respectively pivotally connected to theends of said slide and to said body.
 11. A control valve as defined inclaim 1, wherein said link means comprises a link plate pivotallyconnected to one end of said slide and to said body and another linkmember connected to the other end of said slide and to said body.
 12. Acontrol valve as defined in claim 1, wherein said link means comprises apair of link members respectively having knife edge pivotal engagementwith the ends of said slide and with said body.
 13. A control valve asdefined in claim 1, wherein said link means comprises a link memberhaving knife edge pivotal engagement with one end of said slide andanother link member connected to the other end of said slide and to saidbody.
 14. A control valve as defined in claim 1, wherein said link meanscomprises a tension link member having knife edge pivotal connectionwith one end of said slide and said body and another link memberconnected to the other end of said slide and to said body.
 15. A controlvalve as defined in claim 1, wherein said link means comprises acompression link member having knife edge pivotal connection with oneend of said slide and with said body and another link member connectedto the other end of said slide and to said body.
 16. A control valve asdefined in claim 1, wherein said top wall has one of said inlet andoutlet ports therein, said bottom wall having the other of said inletand outlet ports therein, and including means for removably securingsaid top wall on said body, said link means being interengaged with saidslide and said top wall.
 17. A control valve as defined in claim 1,wherein said top wall has one of said inlet and outlet ports therein,said bottom wall having the other of said inlet and outlet portstherein, and including means for removably securing said top wall onsaid body, said link means being interengaged with said slide and saidtop wall, and said actuator means including a lever extending into saidchamber through a side wall of said body.
 18. A control valve as definedin claim 1, wherein one of said side walls has one of said inlet andoutlet ports therein, the opposing side wall having the other of saidinlet and outlet ports therein, said link means being interengaged withone of said side walls and said slide.
 19. A control valve as defined inclaim 1, wherein one of said side walls has one of said inlet and outletports therein, the opposing side wall having the other of said inlet andoutlet ports therein, said link means being interengaged with one ofsaid side walls and said slide, and said actuator means including alever extending into said chamber through one of said top and bottomwalls.
 20. A control valve as defined in claim 1, wherein one of saidwalls has one of said inlet and outlet ports therein and an opposingwall has the other of said inlet and outlet ports therein, said linkmeans being interengaged between said slide and said one of said walls.21. A control valve as defined in claim 1, wherein one of said walls hasone of said inlet and outlet ports therein and an opposing wall has theother of said inlet and outlet ports therein, said link means beinginterengaged between said slide and said one of said wall and saidopposing wall.